Lake Ontario reaches record, Board continues to respond
Lake Ontario has reached 75.90 m (249.02 ft), exceeding the record peak of 75.88 m (248.95 ft) set in 2017, and will continue rising gradually over the next several days, but is expected to reach this year’s peak within one to three weeks.
The amount of additional rise will be driven mainly by how much precipitation falls across the basin, with an additional 2 to 8 cm (0.8 to 3.1 inches) forecast under the most likely scenarios.
Periods of localized, higher levels are possible during storms and wind events, a number of which have been observed recently.
To better understand impacts, members from the Board and Commissioners from the International Joint Commission have been touring, and will continue to tour the affected areas while conducting listening sessions with elected officials.
Outflows from Lake Ontario continue to be increased as rapidly as conditions allow. Ottawa River flows have been declining slowly, but remain very high. The Ottawa River discharges into the St. Lawrence River and combines with the water released from Lake Ontario near Montreal. This is causing high levels in the lower St. Lawrence River, where many areas have been flooded since April.
The Board, in conjunction with its staff, continues to monitor conditions on an ongoing basis. Information on hydrologic conditions, water levels and outflows, including graphics and photos, are available on the Board’s website and posted to the Board’s Facebook page at https://www.facebook.com/InternationalLakeOntarioStLawrenceRiverBoard (English), and more detailed information is available on its website at https://www.ijc.org/en/loslrb.
Rob Caldwell: (613) 938-5864; Rob.Caldwell@canada.ca
Andrew Kornacki: (716) 879-4349, (716) 352-8669; Andrew.A.Kornacki@usace.army.mil
The International Lake Ontario – St. Lawrence River Board specifies the outflows from Lake Ontario, according to Plan 2014 as required in the 2016 Supplementary Order from the International Joint Commission. This plan was agreed to by the United States and Canada in December 2016 in an effort to improve environmental performance while maintaining most of the benefits provided to other interests by the previous Plan 1958-D, which was in use since 1963. In determining outflows, the Board, in conjunction with its staff, pays close attention to water levels in the Lake Ontario-St. Lawrence River system and on the Great Lakes upstream, and to the effects on stakeholders within the basin .
Water levels vary from year-to-year and throughout the year depending on weather and water supply conditions. Such variations benefit coastal wetlands and are critical to a healthy lake environment, but may at times and depending on individual circumstances increase the vulnerability of shoreline structures and reduce opportunities for recreational boating activities. The Board urges everyone to be prepared to live within the full range of levels that have occurred in the past and of those that may occur in the future. Based on historical observations and projected future conditions, at a minimum, Lake Ontario water levels are expected to range from a high of 75.88 m (248.9 ft.) to a low of 73.56 m (241.3 ft.) at infrequent intervals. However, it is also recognized that future climate conditions are uncertain, and more extreme water levels may be reached and these extremes may occur more often. Levels on the St. Lawrence River tend to vary more widely than on Lake Ontario. Also, these levels do not include the varying local effects of strong winds and wave action that significantly increase or decrease local water levels on both the lake and river, with temporary changes of over half a meter (two feet) possible in some locations.
For more information, please see the Board’s website (ijc.org/loslrb) and Facebook page (https://www.facebook.com/InternationalLakeOntarioStLawrenceRiverBoard).To receive a weekly email about water levels and flows in the Lake Ontario–St. Lawrence River system, please send a blank e-mail message to
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